Fixed some Clang-Tidy checks in Aten Context class (#55942)
Summary:
Clang-Tidy displayed that it's possible to make some methods static and const in Context class. So I made.
It also shows that it has some unused headers from standard libraries included, which i will fix with a next PR.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/55942
Reviewed By: mruberry
Differential Revision: D27766213
Pulled By: bdhirsh
fbshipit-source-id: 4bd9b92c0b8e5c540ac94fbd2bdace64949946e3
